1. Field of the Invention
The invention relates to thermal insulation materials and is directed more particularly to such materials for articles of clothing, including wear for soldiers, sailors, outdoorsmen, and the like.
2. Description of the Prior Art
It is known to provide materials having insulative qualities which preserve body heat of a wearer so as to provide an increased degree of comfort to a wearer in a cold weather setting. Materials having beneficial thermal insulation qualities often are bulky and not structurally stable, so that combinations of different materials are required to provide both conservation of body heat and a stable low bulk structure.
In U.S. Pat. No. 4,167,604, issued Sep. 11, 1979 to William E. Aldrich, a blend of two materials is proposed, including goose down or duckdown for warmth.
In U.S. Pat. No. 4,460,645 issued Jul. 17, 1984 to John C. Jones et al, it is suggested that metal coatings on fibers can provide good heat reflective properties. Suggested coating thickness is in the one micron range.
U.S. Pat. No. 4,537,822, issued Aug. 27, 1985 to Shosuke Nanri et al; U.S. Pat. No. 4,550,046, issued Oct. 29, 1985 to Stephen P. Miller; and U.S. Pat. No. 6,077,597, issued Jun. 20, 2000 to Barbara Pause, all relate to various combinations of layers of diverse materials to provide thermal insulation.
In U.S. Pat. No. 6,382,526, issued May 7, 2002 to Darrell H. Renecker et al and U.S. Pat. 6,520,425, issued Feb. 18, 2003 to Darrell H. Renecker, there is discussed a process and apparatus for providing nanofibers having diameters of one micron and less. Such fibers have been found to be beneficial as refractive or reflective materials for thermally insulating a wearer. However, inasmuch as nanofibers have very small diameters (one micron or less) and provide low bulk, when used in clothing they do not provide a stable or structurally sound material.
Accordingly, there is a need for an insulative material suitable for human wear and having the thermal characteristics required for conserving body heat in very cold surroundings, but also having a strong, stable and low bulk structure. Low bulk is a highly desireable feature for insulation battings. Efficient and low bulk cold weather clothing is particularly important for soldiers in the battlefield. Light weight and low bulk clothing systems greatly improve the mobility and readiness of soldiers. On the commercial side, light weight and low bulk cold weather systems are desirable for outdoor activities and sports.